The overall objectives of this program are to investigate the temporal organization of several physiological and endocrine variables in normal man during prolonged periods of temporal isolation. Particular attention will be paid to differences, if any, in organization of these variables in regard to age and to habitual 24 hour behavior pattern differences, i.e. "morning" and "evening" type individuals. The results of these experiments will serve as a basis for applied studies to clinical sleep disorders, specifically chronic Insomnia and Narcolepsy. To carry out these objectives six groups of subjects will be studied in a "temporal isolation" environment for 25 days. These groups include (1) young (age 21-30) adult normal morning and (2) evening type men, (3) older (ages 50-65) adult normal morning and (4) evening type men and a (5) group of young patients with the Narcolepsy-Cataplexy Syndrome and (6) an older group with chronic insomnia. The following physiological and psychological variables will be measured at frequent intervals, body temperature, plasma cortisol, plasma growth hormone, a self-report estimate of "sleepiness, auditory reaction time, sleep stage polygraphic data, urinary volume, electrolytes, creatinine, 17-OHCS and melatonin. The extensive data obtained under base-line, free-running and entrained conditions will be subjected to data analysis procedures which will include standard graphic display, statistics, a combined linear - nonlinear least squares period analysis, fixed frequency filters and non-sinusoidal waveform eduction procedures.